public class Main {
    public static void main(String[] args) {

        ACommand command =new ConcreteCommand();

        command.setReceiver(new UpperReceiver());
        Invoker textTool = new Invoker(command);
        System.out.println("字母串转大写："+textTool.call("Hello,RainKaze"));

        command.setReceiver(new LowerReceiver());
        textTool = new Invoker(command);
        System.out.println("字母串转小写："+textTool.call("Hello,RainKaze"));

    }
}